It is known from practice to manufacture optical elements and/or forming elements such as lenses, spectacle glasses, molds and the like from a pre-form, manufactured from, for instance, organic or mineral glass which pre-form, on a first side, has a substantially flat or slightly concave, spherical surface with a relatively large bending radius, and, on a second, opposite side, a convex surface with a relatively small bending radius. The convexity of, in particular, the second surface is selected depending on the strength of the desired eventual element such as frame, frame curve and glass curve and of the power of a spectacle glass with respect to myopia (nearsightedness) and hyperopia.
The first surface of this pre-form is milled in a milling machine suitable to that end, while the pre-form is rotated at high speed and the central thickness is reduced and a spherical surface is milled away, so that the radius of the concave surface is reduced. After, approximately, the desired form is obtained, the resulting surface is ground and polished, in order to obtain the desired shape and finish. This polishing is done with a polishing form which is pressed against the surface and which approximately has the desired ultimate shape, whereupon optical element and/or polishing form are rotated relative to each other.
In this known method, relatively much material is removed while during polishing, each time, the polishing form is to be removed to enable measurement and examination of the surface and central thickness, whereupon, if desired, polishing is continued before the optical element is removed from the blocker. This is why this manufacturing method is relatively expensive, labor intensive, time consuming and not always sufficiently accurate. Use of a polishing form is then disadvantageous because with it, at least on a first side, only symmetrically ground, substantially spherical or toric surfaces with parabolic or hyperbolic cross sections can be obtained. Further, this method is not particularly suitable for grinding and polishing highly concave surfaces.
Further, it is known from practice to use pre-form optical elements which, on the whole, already have the outer contour of the desired optical element. Here, both the first (aspherical) and the second surface (aspherical or toric) are of curved design, and by substantially adding material or removing through polishing, in the above-described manner, the curvature of the concave side of the pre-form can be adapted so as to obtain the desired optical element, particularly intended for nearsightedness or semi-nearsightedness. For this method too, it holds that it is relatively expensive and time-consuming and, moreover, not always sufficiently accurate, while furthermore, each time, intermediate measurements are to be performed, during which the element is to be taken from a holder and the operation is to be stopped.
In this description, optical elements are at least understood to include, in particular, spectacle glasses and contact lenses but also optical elements such as lenses for (precision) optics, mirrors and the like. Optical forming elements are at least understood to include forming elements such as molds, machining and non-machining folding tools and the like. The optical elements, optical forming elements and pre-forms thereto may together be indicated as optical objects. The examples given hereinabove should not be construed to be limitative in any way.
The invention contemplates an apparatus for forming and/or working optical elements and/or optical forming elements, with which at least a number of the drawbacks of the state of the art can be obviated.
A further object of the invention is to provide such an apparatus with which optical elements and/or forming elements can be manufactured and/or worked in a rapid and reliable manner.
A further object according to the invention is to provide such an apparatus with which from a limited number of pre-forms, a large number of different optical elements can be obtained.
A further object of the invention is to provide such an apparatus with which indication means, identification means and the like can be provided.
A still further object of the invention is to provide in an apparatus with which optical elements, in particular spectacle glasses and/or contact lenses can be made to measure, in particular matching eye dimensions and/or frame dimensions.
The invention further contemplates providing methods for accurately manufacturing or working optical elements and/or optical forming elements, in particular relatively complex elements in a simple and rapid manner.
The invention further contemplates providing optical elements and/or optical forming elements with relatively complex shapes and surfaces.
These and many objects are achieved according to the invention with the aid of an apparatus, method and optical (forming) element, respectively, as embodied in the claims.